1. Field of the Invention
The present invention relates to a hard coating film that can be advantageously formed on cutting tools (such as tip, drill, and end mill) and jigs (such as forging die and punching die).
2. Description of the Related Art
Conventional cutting tools intended for improved wear resistance consists of a substrate of high speed steel, cemented carbide, cermet, or the like and a hard coating film of TiN, TiCN, TiAlN, and the like formed thereon. Of these hard coating films, that of TiAlN is favorably applied to cutting tools for high speed cutting or hard materials such as hardened steel on account of its very high wear resistance. The recent trend to harder works and higher cutting speed necessitate the development of a new hard coating film with better wear resistance.
An example of recent developments is modification of TiAlN into TiCrAlN (by partial substitution of Ti with Cr) as disclosed in Patent Document 1. According to the disclosure, added Cr increases the compositional ratio of AlN of rock salt structure, thereby contributing to the hardness and oxidation resistance of the coating film. Another example of recent developments is a hard coating film of CrAlN resulting from TiAlN by entire replacement of Ti with Cr, as disclosed in Patent Document 2.
Patent Document 1:
Japanese Patent Laid-open No. 2003-71610 (Claim, Paragraphs 0022 and 0023)
Patent Document 2:
Japanese Patent Laid-open No. Hei-9-41127 (Claims)